Question

An example of Agnatha(jawless vertebrate)/ Cyclostomata is
A. Labeo rohita
B. Scoliodon
C. Rana tigrina
D. Petromyzon

Answer 1

Agnatha are jawless fishes that belong to Vertebrata. Jaw, fins, and stomach are absent in these fishes. Cyclostomes refer to the living group of Agnatha.

Complete answer:
Option A: Labeo rohita or rohu is a fish of the Carp family. They are widely used in aquaculture and used for food. Therefore, this is the incorrect option.

Option B: Scoliodon is a type of shark. They belong to the class Chondrichthyes. They are jawed vertebrates with a pair of fins. Therefore, this is the incorrect option.

Option C: Rana tigrina is a species of frogs commonly known as Indian bullfrog. They belong to the phylum amphibia. Therefore, this is the incorrect option.

Option D: Petromyzon is a type of jawless fish, commonly known as sea lampreys. They have a long, cylindrical, eel-like body. They do not have fins. Therefore this is the correct answer.
The mouth of Petromyzon is round and sucker-like in shape because of the absence of a jaw. They are also known as vampire fish. They are parasitic in nature and drain blood from the fish that is attached to. They are found in coastal seas. Their larval stage is freshwater.
The Agnatha class are the easiest vertebrates. They have a notochord in both adult and larval stages. Their skeleton is made of cartilages. Agnatha is characterized by seven or more paired gills. They are cold-blooded organisms with external Fertilization.

Hence, the correct answer is option (D)

Note: 1)Another example of cyclostomes is Hagfish.
2)They have rudimentary vertebrae and a skull.